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Original question:

BQ76920: Boot sequence

BQ76920: Unable to boot bq76920

Sashi Bhusan Tiwari
Prodigy 135 points
Part Number: BQ76920

Unable to boot bq76920. Applying 3.3 v on TS1 for a moment to boot up. Measured Internal LDO voltage across CAP1 is 3.3 V, and REGOUT voltage is 0.3 V. what could be the problem. Schematic attached.

  • 0
    TI__Guru 54715 points

    Hi Sashi,

    I don't see an issue with the schematic.

    Check that REGSRC pin is soldered to the trace and has the same voltage as the BAT pin.

    Check that REGOUT pin is soldered to the trace.  Check for a short to GND on the REGOUT trace including its capacitor.

    You might also measure the voltage across R19 to see if it looks like a normal operating current or a short somewhere on the regulator, probably REGOUT.

    In case the part may have been damaged in handling or assembly you might try a different board or part on this board.  If you remove the part check for load on REGOUT with the IC removed.

  • 0 in reply to WM5295
    Prodigy 135 points

    Thanks for your prompt reply. BAT and REGSRC pins are not shorted to each other as per the schematic. This may be the cause. I will short both the pins and then check the REGOUT voltage and get back to you.

  • 0 in reply to WM5295
    Prodigy 135 points

    Thanks for your prompt reply. BAT and REGSRC pins are not shorted to each other as per the schematic. This may be the cause. I will short both the pins and then check the REGOUT voltage and will get back to you.